The goal of this research is to elucidate the mechanism of action of membrane receptors for hormones and neurotransmitters at the molecular level. In recent years we have developed a new experimental approach to study receptor - response systems in the cell membrane. It consists of biochemical hybridization of membrane components by membrane fusion. By this procedure a hormone receptor in one cell membrane is coupled to the adenylate cyclase in another cell membrane. The proposed project aims at characterizing and optimizing the membrane fusion system in order to apply it more efficiently. A functional beta-adrenergic receptor will be purified. Its function will be verified at each stage by implantation in a cell membrane with the aid of the fusion procedure. Efficiency of coupling of the implanted receptor to host adenylate cyclase will serve as a measure of function. An attempt will be made to develop the same approach also for analyzing the muscarinic cholinergic and the alpha-adrenergic receptor in rat salivary gland membranes. In the course of working towards these objectives it is hoped to develop experimental systems which could be used by clinical investigators analyzing hormonal disorders.